Structure of persistent current in the presence of a magnetic flux and an electrostatic potential

We present a calculation of persistent current in an ideal mesoscopic ring coupled to an energy and electron reservoir. In this system, elastic scattering and energy dissipation in the ring occur only at the junction coupled to the reservoir. We consider the case where a magnetic flux and an electrostatic potential are applied simultaneously. It is demonstrated that an electrostatic potential modulates the period, amplitude, and phase of the persistent current vs magnetic-flux oscillation. In some electrostatic potentials, we find an h/2e oscillation in the persistent current vs magnetic-flux relation. The current density and density of states in such a system is also derived. The electrostatic potential causes resonance peaks of the current density and density of states vs magnetic-flux oscillations if the magnetic phase shift approaches n. For =0.5 (maximum coupling between the ring and wire), we also derive an analytical expression for the peak height of the current density and density of states vs magnetic flux under constant electrostatic potential. © 1993 The American Physical Society.